Flutter Prediction from Flight Flutter Test Data

Abstract

The most common approach to flight flutter testing is to track estimated modal damping ratios of an aircraft over a number of flight conditions. These damping trends are then extrapolated to predict whether it is safe to move to the next test point and also to determine the flutter speed. In the quest for more reliable and efficient flight flutter testing procedures, a number of alternative data analysis methods have been proposed. Five of these approaches are compared on two simulated aeroelastic models. The comparison is based on both the accuracy of prediction and the efficiency of each method. It is found that, for simple aeroelastic systems, the Nissim and Gilyard method (Nissim, E., and Gilyard, G. B., Method for Experimental Determination of Flutter Speed by Parameter Identification, AIAA Paper 89-1324, 1989) yields the best flutter predictions and is also the least computationally expensive approach. However, for larger systems, simpler approaches such as the damping fit and envelope function methods are found to be most reliable.